modules/nixos: enable pipe operators

`nixd` has support for them and they are honestly really nice to use. `lib.pipe` served us well but having the pipe-operator as is is super nice

modules/nixos/programs/nix/module.nix

@@ -148,6 +148,7 @@ in {
             # Some interesting features.
             # "fetch-closures"
             "no-url-literals"
+            "pipe-operator"
           ];
         }
       ];